How do you spell the Transformers sound?

Ok, my friedn's brother is deaf, and he's a Transformers fan. Recently we've been watching the DVDs and while there is subtitles for the voices (obviously) there isn't a subtitle for the Transformers sound they make when they transform, you know, the one that sounds like: Kch-Kch-Kccchhh-Kchoom! or is it Kacha Kacha Shhhht Shtoom!

He never knew there was a sound involved until we metioned that it's not on the subtitles, so my question is this, how would you spell the sound so a deaf person can understand what it is supposed to sound like?

 

[robotic transformation noises]

leave it up to their imagination

 

I'd go for the first version myself.

 

leave it up to their imagination

I would, but being a fan, and deaf, he'd really like to know...

 

Why not run it through a speach recognition program and see what that says?

It's obviously not idea, bet it's the best I can some up with.

 

I ran it through a speech recognition program, it said "The answer is 42" Whatever that means...

Seriously though, he always thought it was just a sound like a jet flying or a car door closing, he didn't think it was such a unique sound...